Adjustable clamp



p 16, 1969 w. v. BOHLE'R 3,467,352

ADJUSTABLE CLAMP Filed Oct. 21, 1966 5 Sheets-Sheet 1 Fig.1

P 1969 v w. v. BOHLER 3,467,352

' ADJUSTABLE CLAMP Filed 001:. 21. 1966 5 Sheets-Sheet. 5

l N V E N TO R Z WL/gsm 30mm Attorney United States Patent Int. Cl. F16m 13702; A47g 29/00 US. Cl. 248-221 7 Claims ABSTRACT OF THE DISCLOSURE An adjustable clamp has a main housing with two inclined surfaces. Rollers are positioned in respective housings between the inclined surfaces and an object. The main housing is clamped to the object by wedging the rollers between the inclined surfaces and the object.

The invention relates to an adjustable clamp for an article such as a chair having a vertically and laterally adjustable seat, back-rest, or the like, the adjustable clamp being provided for locking or releasing the individual adjustable parts of said chair, said adjustable chair parts being arranged displaceably on a guide rod.

Ever-increasing demands in respect of comfort are being made on chairs, particularly as regards adjustment of individual parts, such as the seat and back-rest. Adjustment in height is required particularly in the case of office furniture, since certain work can be best carried out only when the seat is in a suitable position.

For this reason many chairs have already been made vertically or laterally adjustable, releasable clamping devices being provided to lock the parts of the chair in different positions. However, in order to ensure satisfactory and safe operation, these known clamping devices have had to be made very accurately and with small tolerances. Furthermore, these clamping devices could be fitted only to chairs of tubes which, however, means that the seat and back-rest must be additionally secured against rotation.

Another known device provides a slot in the guide rod, a locking screw projecting through said slot. This device, however, is hard to manipulate, since great strength is required to release it.

It is the aim of the invention to produce an adjustable clamping device which is of simple design and has no very accurate fitting but which in spite of this provides secure retention of the chair parts. According to the invention, this is accomplished in that the clamping device exhibits at least two surfaces directed towards each other and inclined in the direction of displacement, and at least one wedge or rotary element which, in the locked condition at least, lies against an inclined surface, said wedge being held by a housing capable of moving along the guide rod and relatively to said inclined surfaces. This configuration makes easy release of the clamping device possible. An unusual advantage is that said clamping device is not dependent upon the weight-loading, and may therefore also be applied for the lateral adjustment of chair parts. The chair may thus be built up from standard parts, since many identical or similar parts may be used. The arrangement according to the invention makes it possible to use square tubes for the chair frame, in contrast to known designs.

In this connection, the invention expediently provides two wedge-shaped plates facing each other in relation to the direction of the guide rod, and exhibiting a surface inclined to said guide rods, wedges or rotary elements being displaceably mounted between said plates and said guide rod. This construction is of simple design. The lock is released merely by pressure on the housing accommodating the wedges or rotary elements, whereupon the relevant chair part may be moved to any other desired position.

Additional advantageous details and special characteristics of the invention are explained in still greater detail in the following specification, but said invention is not to be restricted to the example set forth. In the drawing:

FIGURE 1 shows a clamping device with its associated attachment device for a back-rest;

FIGURE 2 shows an example of a modified embodiment of the clamping device; and

FIGURE 3 shows a cross sectional view of the clamping device taken along the line 33 in FIGURE 1.

The clamping device 6 consists essentially of plates 7 and 8, of rotary elements 20 and 21 in the form of rollers, and of housings 13 and 14 guiding said rollers. Plates 7 and 8, in the area thereof facing a guide rod 12, exhibit inclined surfaces 23 and 24, against which lie rollers 20 and 21. Said plates 7 and -8 are rigidly screwed to an attachment plate 11 and inclined surface 23 and 24 enclose with guide rod 12 an acute angle, so that said plates are essentially in the form of wedges screwed by means of screws 9 and 10 to said attachment plate 11.

Between said wedges 7 and 8 and guide rod 12 are mounted rollers 20 and 21 which are made to be displaceable in the direction of said guide rod 12. To this end, said rollers 20 and 21 are retained in cage-like housings 13 and 14 which can be pulled in and out after the manner of a drawer. Arranged between these two opposing housings 13 and 14 is a spiral spring 26 which positively holds them apart. Housings 13 and 14 are laterally and outwardly guided by attachment plate 11, and are arranged with a spacing 25 in relation to the guide rod.

Fitted to the side of guide rod 12 opposite clamping device 6 is a bearing plate 5 serving as a counterpart to clamping device 16 and at the same time accommodating a bearing 17, the back-rest attached to plate 18 being adjustable in its oblique position by head 19 pivotally mounted in said bearing.

Now if the clamping device is to be released, housings 13 and 14 are pressed together by their external surfaces 15, 16 in the direction of arrows 1, 2. This forces rollers 20 and 21, which are guided in said housings 13 and 14, away from wedges 7 and 8. Said rollers are therefore no longer pressed against guide rod 12, and locking device 16, and the back-rest associated therewith, are therefore displaced in the direction of arrows 3 and 4. When the back rest reaches the desired height, the housings are released and are moved outwardly in the direction of arrows 3 and 4 by the pressure of spring 26 guided on pins 22 and 27. This results in automatic locking without any outside intervention, since the rollers are pressed against guide rod 12 by inclined surfaces 23 and 24.

FIGURE 2 shows another example of execution of the clamping device, in which housings 13 and 14 enclose wedge-shaped plates 7 and 8. Said housings 13' and 14' exhibit longitudinal slots 28, 29 allowing for the passage of screws 9, 10, so that wedge-shaped plates 7 and 8 may be screwed to attachment plate 11.

Another possible design, not shown, contemplates an externally-actuated eccentric for moving housings 13, 14, a tension spring being arranged between said housings 13, 14 for the purpose of locking clamping device 6. In this arrangement having an eccentric, the housings are pushed apart to release the lock, the inclined surfaces running in directions opposite to those in FIGURES 1 and 2.

Instead of rollers, it is also possible to use balls, in which case, of course, round guide rods may also be used. It is furthermore possible to arrange wedges which are guided in the housings and lie against the steep sur faces of the plates.

An advantage of the clamping device according to the invention is that the individual parts may be made of plastic. This is a simple and cost-saving design. It is also of advantage to make the surfaces of the wedges or rotary elements, and of the inclined surfaces, rough.

The clamping device according to the invention may of course also be used for the lateral displacement of chair parts, and for the vertical adjustment of the seating surface. The adjustment is always stepless. The spring incorporated compensates for machining tolerances. Wear in individual parts does not require the procurement of replacement parts, since the spring compensates for this wear and ensures a firm hold on the guide rod at all times.

I claim:

1. An adjustable clamping device for adjustably fastening an object to an elongated guide rod, comprising:

(a) a main housing having a main opening therethrough formed by two spaced surfaces that are adapted to be positioned on opposite sides of said guide rod;

(b) one of said spaced surfaces having two roller housings slidably positioned thereon, each of said roller housings having an opening therein for receiving a roller;

(c) two wedge plates fastened to a part of said main housing outwardly of said roller housing openings respectively, each of said wedge plates having an inclined surface facing its respective roller housing opening, said inclined surfaces sloping from a location intermediate said wedge plates in the same manner relative to said part of said main housing;

(d) a roller respectively positioned on each of said inclined surfaces, each roller being positioned in a respective roller opening and extending partially therethrough to engage said elongated guide rod;

4 (e) and means attached to said roller housings to urge said housings in opposite directions to cause said rollers to move along said inclined surfaces and be urged against said elongated rod.

2. The clamping device of claim 1 wherein both of said inclined surfaces slope from said intermediate location away from said part of said main housing, and wherein said urging means comprise a compression spring.

3. The clamping device of claim 2 wherein each of said rollers is cylindrically shaped.

4. The clamping device of claim 2 wherein each of said rollers is spherically shaped.

5. The clamping device of claim 1 wherein both of said inclined surfaces slope from said intermediate location toward said part of said main housing, and wherein said urging means comprise a tension spring.

6. The clamping device of claim 5 wherein each of said rollers is cylindrically shaped.

7. The clamping device of claim 5 wherein each of said rollers is spherically shaped.

References Cited UNITED STATES PATENTS 1,751,152 3/1930 Harter 248-412 2,692,748 10/1954 Anderson 248- FOREIGN PATENTS 582,090 8/1933 Germany.

ROY D. FRAZIER, Primary Examiner I. FRANKLIN FOSS, Assistant Examiner US. Cl. X.R. 248-125, 246, 412 

